The present invention relates to a method for evaluating the pitch and voicing of the speech signal in vocoders with very low bit rates.
In known vocoders with low bit rates, the speech signal is cut up into 20 ms and 30 ms frames so that the periodicity or pitch of the speed signal can be determined within these frames. However, during the transitions, this period is not stable and errors occur in the estimation of the pitch and, consequently, in the estimation of the voicing in these parts. Besides, if the speech signal is highly noise-affected by the ambient noise, the evaluation of the pitch is then highly disturbed or even erroneous.